1. Field of the Invention
The invention relates generally to the field of electronics. More particularly, the invention relates to electronic substrates such as liquid crystal diode screens or circuit boards that have at least one optical radiation conducting zone. Specific embodiments of the invention are directed to alignment systems and/or bonding systems that can be utilized in conjunction with the optical radiation conducting zone.
2. Discussion of the Related Art
Anisotropic conducting film (ACF) is an electronically conducting adhesive that only conducts electrons and holes in the Z plane when properly applied. Anisotropic conducting films (ACFs) make it possible to make fine pitch electrical connections between circuit boards and flex connectors, integrated circuits, glass flat panel displays, etc.
In the past, it has been possible to make 0.002" trace and 0.002" space connections, thereby making 250 connections per linear inch. The state of the art of connection density is increasing and is generally limited by the ability of equipment and fixturing to control the bonding process. A common use of this type of connection is in flat panel displays, for example, in the liquid crystal diode (LCD) screens that are often used in portable computers. This ACF bonding is the most common technique used to join tape automated bonding system (TABS) connectors to the LCD glass. The tape automated bonding connectors are coupled to integrated circuits (ICs) that connect logic and power to the row and column drivers to create dots and pixels on the LCD screen.
The quality and reliability of the ACF connection depends on the planarity, pressure and temperature of the bond interface. It is important to control the planarity, pressure and temperature of the ACF bonding process. Most manufacturers of bonding equipment use thermocouple sensors to sense and control the temperature. Thermocouple is a contact type measurement system and are subject to normal process variables that depends on physical sensor contact. In addition, these contact sensors must be placed at least a short distance from the actual bond adhesive or they would get stuck in the bond. Since the contact sensors are located away from the actual bond adhesive, a reading from such sensors measures the temperature of, for example, the bonding head, but not the temperature of the ACF film itself which is of greater interest.
Meanwhile, various remote temperature measurement systems have been developed. The below-referenced U.S. Patents disclose embodiments that were satisfactory for the purposes for which they were intended. The entire contents of U.S. Pat. Nos. 5,145,257; 5,549,756; and 5,893,643 are hereby expressly incorporated by reference into the present application as if fully set forth herein.
Heretofore, the requirements of controlling the planarity, pressure and temperature of an ACF bond have not been fully met. What is needed is a solution that simultaneously addresses all of these control requirements. The invention is directed to meeting all of these requirements, among others.